Erin Tries to Decipher Circadian Rhythm

Erin Tries to Decipher Circadian Rhythm


Okay, so as I’ve mentioned, what first appealed to me about Intermittent Fasting (IF) was how eating in accordance with the body’s natural cycles, or circadian rhythm (CR), can improve how the body functions, leading to better health. Would I mind if this helped in weight-loss too? Of course not. 😊

I’ve been doing a little interweb research about CR, and I feel like I’ve only hit the tip of the iceberg. There is so much information, and it’s really interesting (at least I think so). I’m going to try to break it down here and just go into what applies directly to IF…I’m sure I’ll leave a ton out, but I plan on returning to this topic again. The main guy I’m going to reference in this post is Satchidananda Panda. Go check him out. Besides having maybe the coolest name ever, he’s also done a tone of research on CR and IF, written articles (that have been published), done some TED Talks, etc. Good stuff.

What is Circadian Rhythm?

Basically, over the last lots and lots of years, our bodies have gotten used to the sun rising and setting every day. Our bodies’ systems and functions operate on a 24-hour cycle, which are guided by whether the sun is up or down. If the sun is up, our bodies do things to prepare for hunting and gathering—our energy ramps up, our minds clear.


As the day goes on, our brains and bodies warm up, which makes working and exercising during the day ideal. As the sun starts to set, our bodies start winding down. We get sleepy and during the night our mind and body rest, but certain functions are also triggered, like cell-repair and fat-burning.


This is, of course, how it’s supposed to work in theory. Some of us work the night shift. Some of us are just night owls. Some of us wait until the last minute to do our homework, and then have to stay up all night to get it in on time….anyways….

What does this have to do with Intermittent Fasting?

Just everything. According to Panda, and other smarties, when we eat and don’t eat is just as important to CR as light and dark…maybe even more. When we eat breakfast in the morning (break our fast), it signals to our body that it’s time to get busy. When we stop eating for a long enough period of time, likewise, it signals to our body that it’s time to start repairing and rejuvenating our cells. If this process is triggered by fasting, but we never stop eating long enough to trigger the process, we miss out on this important process. If you eat a late dinner or snack, your body won’t start the repair process until late into the night (if at all depending on times), but it also has to stop in time to start ramping up for the next day. This repair process is, from my understanding, what helps prevent chronic disease, high cholesterol, diabetes, thyroid issues, inflammation, etc…

So ideally, you wake up around the time the sun comes up (who gets to do that?), eat breakfast an hour or two later, and are fully awake mid-morning. This is when you do all your best work at the job. You eat a bit of lunch mid-afternoon, and then exercise late-afternoon to early-evening when your body is all warmed up from the day. Finally you eat a small dinner no later than mid-evening and start turning the lights in your house down and get off that phone and laptop! Your body gets sleepy around the time the sun starts setting, so you head to bed for a great night’s rest while your body heals itself and prepares to start the whole process over the next day. Obviously this isn’t 100% practical for most of us…it’s not for me.

I think the point is to make it work for you and your schedule. To some degree, from what I’ve read, you can alter your CR by altering when you sleep and eat. I have to get up before the sun rises to get to work on time, but I also go to bed earlier than many (except on homework nights. Sigh.). As I’ve mentioned, I am eating between 10am and 6pm, which seems to be working for me pretty well so far. I eat a pretty big breakfast at 10am, a lighter lunch, and then a pretty big dinner. After some of the reading I’ve been doing, though, I think I’m going to start eating a big breakfast, medium lunch, and light dinner. Our bodies burn the most fuel in the morning, so breakfast is less likely to be turned into sugar and fat than dinner.


Before I forget, let me tell you about these mice


One of the compelling trials that Panda has done during his research, is an IF trial with mice. In the trial, two sets of mice are given the exact same food in the same quantity. One group of mice is allowed to eat their food any time of day. The second group is only allowed to eat their food in a limited window of time (I want to say a 10 hour window…but don’t quote me on that. I know, it’s super-lazy of me to not just go look, but here we are.). I’m sure you see where this is going. The mice that ate all times of the day had more health problems, and more body fat. The mice that ate within a limited window—even though it was the same amount and type of food—were healthier and had lower amounts of fat on their bodies. Panda and a partner also conducted a less clinical test on humans that involved participants to self-report via an app. The humans showed similar results as the mice. What I gather from these results is that our (and the mice’s) bodies function better on this limited eating schedule…for the reasons listed above.

Let’s wrap this up

Like I said, this is a tiny, and overly simplified, bit of the information available about CR and how it relates to IF…or vice versa? I feel like I’m learning a ton, and plan on doing some more digging, so you can look forward to (or not) more posts along these lines. Some things I’m taking away from this CR info-dive that I need to work on:

  • I’m going to try to eat a lighter dinner
  • I probably need to not sleep with the TV on…
  • I definitely need to quit checking my phone every time I wake up
  • Should I quit giving my dog’s treats before bed?

Let me know if you thought this article was interesting, boring, made you want to do your own research so you could correct me on all the things… 😊  I want to hear your thoughts, so leave me a comment! ✌